Heat ¼ cup oil in a kadai, add in tomatoes, tamarind, salt and mix well. cover and cook till it softens.

Keep cooking till oil separates. Cool it down and take it in a blender, puree till coarse.

Heat ¼ cup of oil in the same pan, add mustard, urad dal and asafoetida and let it sizzle.

Add the tomato puree, add in chilli powder and cook till oil separates.

Cool it down.

Store in an air tight container in fridge.